Commit 689be439 authored by David S. Miller's avatar David S. Miller
Browse files

[NET]: Remove gratuitous use of skb->tail in network drivers. 



Many drivers use skb->tail unnecessarily.

In these situations, the code roughly looks like:

	dev = dev_alloc_skb(...);

	[optional] skb_reserve(skb, ...);

	... skb->tail ...

But even if the skb_reserve() happens, skb->data equals
skb->tail.  So it doesn't make any sense to use anything
other than skb->data in these cases.

Another case was the s2io.c driver directly mucking with
the skb->data and skb->tail pointers.  It really just wanted
to do an skb_reserve(), so that's what the code was changed
to do instead.

Another reason I'm making this change as it allows some SKB
cleanups I have planned simpler to merge.  In those cleanups,
skb->head, skb->tail, and skb->end pointers are removed, and
replaced with skb->head_room and skb->tail_room integers.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Acked-by: default avatarJeff Garzik <jgarzik@pobox.com>
parent f835e471

drivers/net/3c515.c

+2 −2
Original line number Diff line number Diff line
@@ -822,7 +822,7 @@ static int corkscrew_open(struct net_device *dev) 
				break;	/* Bad news!  */

			skb->dev = dev;	/* Mark as being used by this device. */

			skb_reserve(skb, 2);	/* Align IP on 16 byte boundaries */

			vp->rx_ring[i].addr = isa_virt_to_bus(skb->tail);

			vp->rx_ring[i].addr = isa_virt_to_bus(skb->data);

		}

		vp->rx_ring[i - 1].next = isa_virt_to_bus(&vp->rx_ring[0]);	/* Wrap the ring. */

		outl(isa_virt_to_bus(&vp->rx_ring[0]), ioaddr + UpListPtr);
@@ -1406,7 +1406,7 @@ static int boomerang_rx(struct net_device *dev) 
				break;	/* Bad news!  */

			skb->dev = dev;	/* Mark as being used by this device. */

			skb_reserve(skb, 2);	/* Align IP on 16 byte boundaries */

			vp->rx_ring[entry].addr = isa_virt_to_bus(skb->tail);

			vp->rx_ring[entry].addr = isa_virt_to_bus(skb->data);

			vp->rx_skbuff[entry] = skb;

		}

		vp->rx_ring[entry].status = 0;	/* Clear complete bit. */

drivers/net/3c59x.c

+3 −3
Original line number Diff line number Diff line
@@ -1802,7 +1802,7 @@ vortex_open(struct net_device *dev) 
				break;			/* Bad news!  */

			skb->dev = dev;			/* Mark as being used by this device. */

			skb_reserve(skb, 2);	/* Align IP on 16 byte boundaries */

			vp->rx_ring[i].addr = cpu_to_le32(pci_map_single(VORTEX_PCI(vp), skb->tail, PKT_BUF_SZ, PCI_DMA_FROMDEVICE));

			vp->rx_ring[i].addr = cpu_to_le32(pci_map_single(VORTEX_PCI(vp), skb->data, PKT_BUF_SZ, PCI_DMA_FROMDEVICE));

		}

		if (i != RX_RING_SIZE) {

			int j;
@@ -2632,7 +2632,7 @@ boomerang_rx(struct net_device *dev) 
				pci_dma_sync_single_for_cpu(VORTEX_PCI(vp), dma, PKT_BUF_SZ, PCI_DMA_FROMDEVICE);

				/* 'skb_put()' points to the start of sk_buff data area. */

				memcpy(skb_put(skb, pkt_len),

					   vp->rx_skbuff[entry]->tail,

					   vp->rx_skbuff[entry]->data,

					   pkt_len);

				pci_dma_sync_single_for_device(VORTEX_PCI(vp), dma, PKT_BUF_SZ, PCI_DMA_FROMDEVICE);

				vp->rx_copy++;
@@ -2678,7 +2678,7 @@ boomerang_rx(struct net_device *dev) 
			}

			skb->dev = dev;			/* Mark as being used by this device. */

			skb_reserve(skb, 2);	/* Align IP on 16 byte boundaries */

			vp->rx_ring[entry].addr = cpu_to_le32(pci_map_single(VORTEX_PCI(vp), skb->tail, PKT_BUF_SZ, PCI_DMA_FROMDEVICE));

			vp->rx_ring[entry].addr = cpu_to_le32(pci_map_single(VORTEX_PCI(vp), skb->data, PKT_BUF_SZ, PCI_DMA_FROMDEVICE));

			vp->rx_skbuff[entry] = skb;

		}

		vp->rx_ring[entry].status = 0;	/* Clear complete bit. */

drivers/net/8139cp.c

+2 −2
Original line number Diff line number Diff line
@@ -596,7 +596,7 @@ rx_status_loop: 


		mapping =

		cp->rx_skb[rx_tail].mapping =

			pci_map_single(cp->pdev, new_skb->tail,

			pci_map_single(cp->pdev, new_skb->data,

				       buflen, PCI_DMA_FROMDEVICE);

		cp->rx_skb[rx_tail].skb = new_skb;
@@ -1101,7 +1101,7 @@ static int cp_refill_rx (struct cp_private *cp) 
		skb_reserve(skb, RX_OFFSET);



		cp->rx_skb[i].mapping = pci_map_single(cp->pdev,

			skb->tail, cp->rx_buf_sz, PCI_DMA_FROMDEVICE);

			skb->data, cp->rx_buf_sz, PCI_DMA_FROMDEVICE);

		cp->rx_skb[i].skb = skb;



		cp->rx_ring[i].opts2 = 0;

drivers/net/82596.c

+7 −7
Original line number Diff line number Diff line
@@ -546,11 +546,11 @@ static inline void init_rx_bufs(struct net_device *dev) 
		rbd->b_next = WSWAPrbd(virt_to_bus(rbd+1));

		rbd->b_addr = WSWAPrbd(virt_to_bus(rbd));

		rbd->skb = skb;

		rbd->v_data = skb->tail;

		rbd->b_data = WSWAPchar(virt_to_bus(skb->tail));

		rbd->v_data = skb->data;

		rbd->b_data = WSWAPchar(virt_to_bus(skb->data));

		rbd->size = PKT_BUF_SZ;

#ifdef __mc68000__

		cache_clear(virt_to_phys(skb->tail), PKT_BUF_SZ);

		cache_clear(virt_to_phys(skb->data), PKT_BUF_SZ);

#endif

	}

	lp->rbd_head = lp->rbds;
@@ -816,10 +816,10 @@ static inline int i596_rx(struct net_device *dev) 
				rx_in_place = 1;

				rbd->skb = newskb;

				newskb->dev = dev;

				rbd->v_data = newskb->tail;

				rbd->b_data = WSWAPchar(virt_to_bus(newskb->tail));

				rbd->v_data = newskb->data;

				rbd->b_data = WSWAPchar(virt_to_bus(newskb->data));

#ifdef __mc68000__

				cache_clear(virt_to_phys(newskb->tail), PKT_BUF_SZ);

				cache_clear(virt_to_phys(newskb->data), PKT_BUF_SZ);

#endif

			}

			else
@@ -840,7 +840,7 @@ memory_squeeze: 
				skb->protocol=eth_type_trans(skb,dev);

				skb->len = pkt_len;

#ifdef __mc68000__

				cache_clear(virt_to_phys(rbd->skb->tail),

				cache_clear(virt_to_phys(rbd->skb->data),

						pkt_len);

#endif

				netif_rx(skb);

drivers/net/dl2k.c

+4 −4
Original line number Diff line number Diff line
@@ -547,7 +547,7 @@ rio_timer (unsigned long data) 
				skb_reserve (skb, 2);

				np->rx_ring[entry].fraginfo =

				    cpu_to_le64 (pci_map_single

					 (np->pdev, skb->tail, np->rx_buf_sz,

					 (np->pdev, skb->data, np->rx_buf_sz,

					  PCI_DMA_FROMDEVICE));

			}

			np->rx_ring[entry].fraginfo |=
@@ -618,7 +618,7 @@ alloc_list (struct net_device *dev) 
		/* Rubicon now supports 40 bits of addressing space. */

		np->rx_ring[i].fraginfo =

		    cpu_to_le64 ( pci_map_single (

			 	  np->pdev, skb->tail, np->rx_buf_sz,

			 	  np->pdev, skb->data, np->rx_buf_sz,

				  PCI_DMA_FROMDEVICE));

		np->rx_ring[i].fraginfo |= cpu_to_le64 (np->rx_buf_sz) << 48;

	}
@@ -906,7 +906,7 @@ receive_packet (struct net_device *dev) 
				/* 16 byte align the IP header */

				skb_reserve (skb, 2);

				eth_copy_and_sum (skb,

						  np->rx_skbuff[entry]->tail,

						  np->rx_skbuff[entry]->data,

						  pkt_len, 0);

				skb_put (skb, pkt_len);

				pci_dma_sync_single_for_device(np->pdev,
@@ -950,7 +950,7 @@ receive_packet (struct net_device *dev) 
			skb_reserve (skb, 2);

			np->rx_ring[entry].fraginfo =

			    cpu_to_le64 (pci_map_single

					 (np->pdev, skb->tail, np->rx_buf_sz,

					 (np->pdev, skb->data, np->rx_buf_sz,

					  PCI_DMA_FROMDEVICE));

		}

		np->rx_ring[entry].fraginfo |=

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